Concrete construction



I April 1940- FQALLBRIGHT 2,196,158

CONCRETE CONSTRUCTION Filed Sept. 8, 193a 5 Sheets-Sheet 1 ,fzg veflfior\K [aw/1v F ALLB/E/GHT 6 WEM Y \S) d f/t'orweg A ril 2, 1940.

v n g 1110677502 [ow/Iv fT ALLBR/GHT 29 WSW April 2, 1940.

E. F. ALLBRIGHT 2,196,158

CONCRETE CONSTRUCTION Filed Sept. 8, 1938 5 Sheets-Sheet 3 llrll'-Iwvewlbr [aw/N F flLLBE/GHT April 2, 1940- E. F. ALLBRIGHT 2,196,158

CONCRETE CONSTRUCTION Filed Sept. 8, 1938 5 Sheets-Sheet 4 191 view For[am/v F. ALLBK/GHT \i I y aw a/tfiommg April 2, 1940- I E. F. ALLBRIGHT2,196,158

CONCRETE CONSTRUCTION Filed Sept. 8, 193a s Sheefs-Sheet 5 I77U677Z27i"[ow/1v E ALLBR/GHT Patented Apr. 2, 1940 UNITED STATES PATENT OFFICECONCRETE CONSTRUCTION Edwin F. Allbright, Wollaston, Mass, assignor toGrid Flat Slab Corporation, Boston, Mass., a, corporation ofMassachusetts Application September 8, 1938, Serial No. 228,937

'7 Claims.

This invention relates to improvements in concrete construction.

More particularlyit relates tothe centering of forms and laying of steelreinforcements for concrete floors, roofs, and the like, of the generaltype disclosed in my Letters Patent No. 1,307,031, dated June 17, 1919,wherein recesses are provided in the under face of .the concrete flooror other horizontal structure.

According to my said Letters Patent, a multiplicity of flanged sheetmetal domes may be set next to each other with their respective flangesabutting, thus spacing the domes uniformly over the area where, theconcrete is to be poured. The same dome-shaped forms may be utilized inthe practice of my present invention, although the structural featuresof my novel reinforcement are not to be regarded as limited to the useof any particular device or devices for producing the recesses in theunder face of the concrete.

Concrete construction of the sort to which the invention relates willhave the under face deeply recessed at uniform intervals throughout itsfull area, except that a solid plinth may occur ateach location where asupporting column rises from below.

Between the recesses the walls of the recesses constitute intersectingribs of corn crete; and the invention relates to improvements in thereinforcing of these relatively narrow ribs as well as to thereinforcing of the concrete structure as a whole.

Heretofore, the main reinforcing bars employed have been of greatlength-long enough to reach across the solid plinth of concrete over acolumn, and across the intervening region between that plinth and thenext plinth, and across that next plinth also.

The parts of the bars ture in which all reinforcing bars may bestraight. This eliminates the cost of bending them. Also, the mainreinforcing bars may be considerably shorter than those consideredrequisite heretofore.

This eliminates the difliculties and expense of handling such extremelengths. This feature is of substantial importance, for the span isoften 24 feet between centers of plinths, and the plinths may be 10 feetwide, making a length of bar approaching 40 feet, which, in steel ofinch diameter is awkward and extra expensive to transport and handle.

With the down-bending and the return upbending expense eliminated,another object is to provide for effective non-sagging suspension of thelow bars at their ends.

These objects being attained, it also results from the invention thatthe reinforcing bars can be more easily placed than according to priorpractices, and With less incidental expense.

A further object is to provide improved means for centering and fortemporarily supporting the dome-shaped forms, and for improving theappearance of the recessed face of a concrete ceiling. 20

Still another object is to provide for varying the spacing of thedome-shaped forms as may be desired.

The stated'objects, and the other advantageous results whichcharacterize the invention, are attained by emp oying a series ofstraight and stiff bars, herein called raising bars. In a preferredembodiment these rest on the tops of the dome forms, and are supportedthereon a little above the plane of those tops, and one of them liesalong each edge of each plinth. This makes a huge mesh or skeleton,usually rectangular, of raising bars, in which one series of barsextends in parallelism in one direction; and another series is of barswhich extend in parallelism at right angles to the first; each barcrossing over a succession of tops of domes and crossing over valleysbetween thesuccessive domes in the series of domes on'which it rests.

Considering any row of domes which is in a 4 position bordering a sideof a plinth, there will be valleys between the successivedomes of thatrow; and in each valley thus crossed by the raising bar resting on thisrow of domes, wire stirrups hang down into the valley from that bar andsupport the ends ofthe pairs of reinforcing rods which, deep down in thevalley, extend from that plinth to its neighbor. That is in the case ofvalleys which extend only from plinth to plinth. Other valleys, notencountering any plinth, extend throughout the full dimension of thefloor or roof. But the said stirrups support the ends of only those barswhich extend from one plinth to another, and these rods in turn maysupport the rods extending through areas where they encounter noplinths. When the concrete has been poured, these rods make straighttensile reinforcements for the concrete close to the lower face of therib, for each rib is the concrete filling of what was a valley betweendomes. Similar reinforcing rods, for the concrete at the upper face ofthe roof or floor, extend in two directions across above each plinth atthis high level; and they have their ends supported on the said skeletonof raising bars in positions bordering the sides of the plinths.

This provision for utilizing wire stirrups for suspension of lower rodsfrom higher bars, permits the building of an efiective net-work ofreinforcing elements, in which, when incorporated in the pouredconcrete, pairs of straight bars may cross each other near the surfaceswhere stress is greatest, and provide a superior type of reinforcement.These stirrups are also essential in taking care of the shearingstresses in the ribs, when these stresses are too great to be carried bythe concrete alone.

The dome-shaped forms may be centered and temporarily supported, as inmy said Patent No. 1,307,031, by shoring whose individual boards may bespaced apart a distance approximating the outside width of a dome-form,from flange edge to flange edge, and which extend in parallelism in onedirection only across the area of the floor or ceiling. The dome flangesmay abut each other along these boards; or wide boards may be employedpermitting spacing apart of the dome flanges as may be desired. In thislatter case, according to the invention, structural plywood may beemployed for overlapping slightly the edges of flanges, and formaintaining the domes until the concrete has been poured. When thetemporary elements, including the plywood, are removed, the ribs ofconcrete between recesses are left with a surface aspect resemblingpanelling.

In the case where the dome flanges abut, temporary marking strips may beemployed to leave impressions along joints for decorative effect.

It is intended that the patent shall cover, by suitable expression inthe appended claims, whatever features of patentable novelty exist inthe invention disclosed.

In the accompanying drawings, in which one illustrative embodiment ofthe invention, is shown:

Figure 1 is a top plan of a concrete construction for a floor embodyingfeatures of the invention, the concrete being absent from one area, toshow in full lines the raising bars. reinforcing rods. stirrups anddomes;

Figure 2 is a top plan, on a larger scale, showing upper reinforcingrods blackened and showing lower reinforcing rods cross-hatched, forclearness of portrayal of the overlapping and crossing reinforcing rodsnear the upper surface of cement over a plinth, and of the overlappingand crossing reinforcing rods near the lower surface of cement in themid-region between four plinths;

Figure 3 is an elevation, enlarged still more, in section on 3-3 ofFigure 2;

Figure 4 is a view similar to Figure 3, in section on 4--4 of Figure 2;

Figure 5 is a perspective of one of the stirrup units;

Figure 6 is a top plan of a structure, at a stage prior to pouring ofthe concrete, having my improved arrangement of shoring, the dome-shapedforms being absent from a portion of the area, for clearness;

Figure 7 is an elevation in section, as if on l'i of Figure 6; butshowing Where the concrete will be located relative to the reinforcingrods;

Figure 8 is a view similar to Figure '7, in section as if on 88 ofFigure 6;

Figure 9 is a fragmentary top plan of associated dome-shaped formshaving small disks and triangular ribs for securing the forms, and forleaving decorating imprints on the under faces of the concrete ribsbetween recesses;

Figure 10 is an elevation, on an enlarged scale, in section on lf3-ll ofFigure 9;

Figure 11 is a top plan of an arrangement in which the dome flanges arespaced apart;

Figure 12 is an elevation, on an enlarged scale, in section on l2l2 ofFigure 11; and

Figure 13 is an elevation of fragments of adjoining domes, in section,showing reinforcing rods supported from below.

Referring to the drawings, the lightly dotted squares Hi of Figure 1which is a top plan of floor, represent recesses in the under side ofthe concrete floor construction, and the portions l2 between squares ifirepresent the concrete Walls of those recesses, being in the nature ofcrisscross depending ribs among the recesses, occupying the spacesmarked 39 in Figures 3 and 4.

Figure 1 includes a full representation of two plinths and a partialrepresentation of two others, each having the reference character 14. Inthe structure represented, the tensile stresses resulting from negativebending moments are greatest at the plinths, and the tensile stressesresulting from positive bending moments are greatest in the regionmidway between the four plinths.

According to the invention, reinforcing rods are arranged in pairs, withthe pairs It crossing each other at each plinth, near the upper surfaceof concrete, and with the pairs 18 crossing each other at saidmid-region between plinths, near the lower surface of each rib ofconcrete.

The enlarged plan, Figure 2, shows my improved structure prior to thepouring of concrete. The upper pairs of reinforcing rods l6 areblackened, and the lower pairs of reinforcing rods l8 are cross-hatched,in order to show clearly the crossing of pairs at the upper level. overa plinth, and the crossing of pairs at the lower level in the mid-regionbetween plinths. Figure 2 illustrates also that the region interveningbetween any two plinths does not have the pairs of reinforcing rodscrossing each other at either upper or lower levels, but has themextending in direction between the plinths at the lower level, and hasthem at the upper level extending at right angles to those at the lowerlevel. Of course additional reinforcing rods may be used, but more areconsidered not necessary.

According to the invention, recessed dome forms 20 are first laid on asuitable temporary supporting structure 2] (Figure 3). Then a skeltonraising bar structure is laid upon the domes, consisting of the parallelraising bars 22. which are each disposed medially above a row of domes20 that lies next to one side of a plinth l4, and of the parallelraising bars 24 at a right angle with the bars 22, which are disposedlike bars 22 on rows of domes lying along the other two sides of aplinth, crossing bars 22.

The bars 22, 24, which are primarily hanger supports, may be as long oras short as may be convenient and practicable in any particular case.Assuming a system of domed forms 20 to be in place, the bars may berested on and spaced a little above the domes 20 (Figures 3, 4) by meansof rough-surfaced briquettes 26 set on the domes at suitable intervalsalong the extent of a bar 22, 24. As portrayed in the drawings, abriquette 26 is set on every other dome 20, along the extent of each bar22, 24. The bars rest directly on these briquettes, and/are spacedthereby from one to two inches or so above the domes, depending upon thethickness to which the concrete is to be poured over the tops of thedomes, which ordinarily may range from two to four inches. Consequently,the length of the individual bars is quite unimportant.

After this skeleton support structure 22, 24 has been laid, stirrupunits 28 are suspended from the bars 22, 24, one unit being placed tobecome embedded in each portion of a concrete rib 30, which ends at amargin of a plinth, one such stirrup being hung in the first section ofevery valley wherein a rib 36 will start away from a plinth.

As seen in Figure 5, each stirrup 28 may be a fabricated unit comprisinga series of U'-shaped wires 28 secured together in spaced parallelrelation and in alignment by the wire 28 welded to the bottom of each U,and by the wires 28 welded high up on the respective arms of the U, theend portions of the arms being bent into hooks to engage over the wires23' and to extend obliquely downward as at 28 Two of these hook portions28 preferably an opposed pair near the middle of the unit, are bent alittle sidewise out of the plane of the remainder of their particular Uelement 28 thereby to constitute hooks, one at each side of the unit,for engaging also over one of the bars 22, or 24 which will hold theunit group of Us suspended until it becomes embedded within one of theconcrete ribs 30.

The lower pairs of reinforcing rods l8 are positioned to be near thelower surfaces of the ribs 30, by being hung in these stirrup units 28suspended from raising bars 22 or.24.

The upper reinforcing rods IB are positioned to be near the ultimate topsurface of the concrete, and are shown resting upon the raising bars 22or 24, depending upon the direction of their extent.

All of the reinforcing rods i6, 18 may be of the same length in astructure such as that here represented, which has square plinths I4 andwhich has the distance between plinths equal to the distance across aplinth. Actually the distance across a plinth. usually will be somewhatless than the distance between plinths. For example, assuming a distanceof 24 feet from center to center of plinths, the width of each plinthordinarily will be about four-tenths of that distance, which in theassumed case would be nine and six-tenths feet. And thus the distancebetween plinths would be fourteen and four-tenths feet. The reinforcingrods 16, I8 preferably will be a little longer than this distancebetween plinths, so that the rods i8 which extend between plinths, atthe lower level, have their ends extending a little into the solidconcrete of the plinths; and so that the rods I6 which extend acrossplinths and beside plinths, at the higher level, project across the ribnext beyond the raising bar 22 or 24 on which they are resting.

After the reinforcing structure has been placed, and the concrete pouredand set sufficiently, the

dome-shaped forms may be removed, leaving an under surface deeplyrecessed uniformly except at the regions of the solid plinths I4. As theforms are removed, the briquettes 26, on which the raising bars 22, 24were originally laid, remain embedded in the concrete, held in byengagement of the concrete at the rough surfaces of the briquettes. Therecessed construction thus produced effects a considerable saving ofconcrete by eliminating concrete which is not needed for strength,thereby assuring that the concrete which is used will Work-more nearlyup to its maximum carrying capacity. Also the recessed constructionrelieves the concrete of the burden of carrying an excessive andunnecessary weight of concrete.

The recessed surface of concrete may be finished to produce a desiredceiling effect. In some cases the recesses may be preserved visible,while in other cases it may be preferred to cover the recessed surfaceto gain a plane effect.

Any practicable embodiment of the disclosed concrete reinforcingfeatures, as herein disclosed, will include means for temporarilysupporting and centering the dome-shaped forms 20, and one such as isrepresented generally at 2| in Figure 3.

Figures 6-8 illustrate an embodiment of the invcntion in which the domeforms 20 rest on, and are centered on, shoring which comprises theparallel boards spaced apart on centres at a distance equal to theoutsidewidth of a dome form 20, and all extending in the same directionacross the area of floor or ceiling which is to be constructed. Theseboards 32 may be themselves supported and maintained in any suitablemanner, as by the joists 34, set edgewise, and extending across thedirection in which the boards 32 extend (Figures 6, 8). The dome forms20 rest directly on the boards 32 and are supported thereby along twosides only, and may be secured by a nail 36 or the like at each corner,the nail passing through the space at the juncture of the slightlyrounded corners of dome flanges, with its head engaging and holding acorner flange of each of the four domes at the particular juncture.

The raising bars 22 and 24' of this embodiment serve the same functionas the bars 22, 24 previously described. The reinforcing rods l8 crosseach other in pairs in positions to be deep down in the ridges ofconcrete which border the recesses in a completed floor or ceiling, inregions between wall or beam supports; and the reinforcing rods l6 crosseach at the higher level adjacent to the walls, and extend in onedirection across beam supports. outside wall is represented at A and aninside wall at B; and a beam is represented at C in Figures 6 and 8. Theraising bars 22' are shown resting directly on the dome forms 20, andthe raising bars 24 are supported on the bars 22, being laid at 90angles thereto. The stirrup units 23 are suspended from the raising bars22 which are adjacent to the walls A and B, and from the raising bars 24which are adjacent to the beam C. The pairs of reinforcing rods H! whichextend in. directions between walls and between beams are supported neartheir ends in these stirrups.

Figures 9 and 10 illustrate means for making decorative impressions inthe under faces of the ribs of concrete bordering the recesses. For thispurpose a disk element Ml may be secured, as by a nail 42, over abuttingcorners of dome flanges, at each place where a plurality of such cornerscome together. Each disk has four In Figures 6 and 7, an

sockets therein for receiving the ends of bars 44, 'each'of which may betriangular in cross-section, and each extending along a line of edgeabutment of dome flanges, from one disk 40 to another. The disks leaveround impressions in the concrete and the bars 44 leave lineardepressions in the concrete, when the domes and their appurtenances areremoved.

Figures 11 and 12 show an arrangement of dome forms wherein the domeflanges may be spaced apart as desired. Plywood panelling 46 extendsbetween the domes of forms 20 and slightly overlaps the spaced-apartflanges. The plywood panels are fitted to come nicely together, as seenin Figure 11, and disks 48 may be nailed at each juncture to hold thepanels in place, and the panels hold the dome for. s properly placedduring pouring and setting of the concrete. When the forms and plywoodare removed, the concrete surfaces bordering recesses present a panelledeffect.

Ordinarily the one-inch reinforcing rods IE, l8 can span the spacebetween raising bars 22 or 24 without impracticable sagging. Butadditional raising bars may be employed if desired.

The lower reinforcing rods i8 may, if desired, be supported on wirechairs 50 which may stand on the flanges of domes, as indicated, inFigure 13. However, the supporting of these rods E8 in stirrups ispreferred because both the rods and the stirrups are entirely enclosedand hidden when the concrete is poured.

I claim as my invention:

1. A structure for the forming and reinforcing of concrete floors andthe like horizontal slabs recessed on their under sides, comprising, incombination, removable recess-forming domes spaced apart on temporarysupports and aligned in two sets of parallel rows extending indirections which cross each other; raising bars, each extending alongand supported by the domes of a row; high level reinforcing rods,approximately straight, crossing and supported by one parallel set ofsaid raising bars; low level reinforcing rods, approximately straight,extending in valleys between rows of domes; and stirrups located in saidvalleys for supporting there the said low rods; the said stirrups of avalley being hung on raising bars by being hooked over those bars whichextend in a direction crossing that direction in which that valleyextends; said temporary supports and said domes being removable from thestructure after the concrete has been poured and has at least partiallyset, leaving said bars and rods remaining as reinforcing elements in theconcrete.

2. A structure for the forming and reinforcing of concrete floors andthe like horizontal slabs recessed on their under sides, comprising, incombination, removable recess-forming domes spaced apart on temporarysupports and aligned in two sets of parallel rows extending indirections which cross each other; raising bars, supported by the domes;spacing elements resting on the tops of domes across which the raisingbars are laid for supporting said bars at an elevation above the tops ofthe domes; high level reinforcing rods, approximately straight, crossingabove and supported by resting on said raising bars; low levelreinforcing rods, approximately straight, extending in valleys betweenrows of domes; and means located in said valleys for supporting therethe said low rods; said temporary supports and said domes beingremovable from the structure alter the concrete has been poured and hasat least partially set leaving said bars and rods remaining asreinforcing elements in the concrete, and leaving said spacing elementspermanently embedded in the concrete.

3. A structure for the forming and for reinforcing concrete floors andthe like horizontal slabs as in claim 1 in which each stirrup comprisesa plurality of U-shaped wires connected together in parallelism andhaving hooks for hanging the stirrup on a said raising bar; said U-wiresextending down in a valley for supporting the reinforcing rods in the U.

4. A structure for the forming and reinforcing of concrete floors andthe like horizontal slabs as in claim 2, wherein regions for theconcrete plinths are devoid of the domes, and said raising bars extendalong each side of each such plinth region, and wherein the reinforcingrods which extend between the regions for plinths are of length fortheir end portions to extend and be embedded in the concrete of theplinths.

5. A structure for forming and for reinforcing concrete floors andceilings as in claim 2, wherein the dome forms are rectangular, and abase flange extends along each side of each for automatic spacing apartof domes by the abutting of flanges of adjoining dome forms; andwherein, at the corner junctures of adjoining flanges, a securingelement engages a corner of each flange; and a recess-forming stripextends along each line of abutting juncture of flange edges, the stripbeing between and temporarily held by said securing elements.

6. A structure for the forming and reinforcing of concrete floors andthe like horizontal slabs as in claim 2, wherein the dome-forms havebase flanges which are spaced apart in the directions of said rows ofdomes, and in which stifi sheet material is temporarily secured in thevalleys between domes, bridging the spaces between flanges, and securingthe domes in their said alignment in rows.

7. A structure for the forming and reinforcing of concrete floors andthe like horizontal slabs as in claim 2, wherein the dome-forms havebase flanges which are spaced apart in the directions of said rows ofdomes, and in which sheets of structural plywood are temporarily securedin the valleys between domes, bridging the spaces between flanges, andsecuring the domes in their said alignment in rows.

EDWIN F. ALLBRIGHT.

